Electromagnetic relay



April 30, 1963 N. H. KOERTGE 3,088,007

ELECTROMAGNETIC RELAY Filed Aug. 31. 1960 3 Sheets-Sheet 1 April 30,1963 N. H. KOERTGE 3,088,007

ELECTROMAGNETIC RELAY Filed Aug. 31, 1960 3 Sheets-Sheet 2 April 1963 N.H. KOERTGE 3,088,007

ELECTROMAGNETIC RELAY Filed Aug. 31, 1960 5 Sheets-Sheet 3 3,083,007ELECTROMAGNETIC RELAY Nobel H. Koertge, Elm Grove, Wis., assignor toCutler- Hamrner, lnc., Milwaukee, Wis, a corporation of Delaware FiledAug. 31, 19cc, Ser. No. 53,200 3 Claims. (Cl. zoo-a7 This inventionrelates to an improved electrical relay.

One object of this invention is to eliminate the magnet frame tolerancesfrom consideration in computing the Wear allowance of a relay.

Another object is to provide such a relay which is inexpensive andeasily assembled.

Still another object is to reduce contact bounce in the relay.

A further object is to provide a stationary contact arrangementaffording ready convertibility from normally open to normally closedcontact operation.

The first object is accomplished by providing an aperture in the magnetframe through which the core may pass so that its bottom end can besecured directly to a molded base (on which tolerances can be closelyheld) instead of to the frame (which inherently has wider tolerancesthan a molded piece).

The second object is accomplished partly by mounting the coil on thecore against a top of the core enlarged to prevent the coil from slidingoff and further by constructing the other parts of the relay so that thearmature lever slides onto the end of the magnet frame and extends intoengagement with a movable contact carrier. Then this whole assembly iscompleted by snapping a spring plate into engagement between the contactcarrier and magnet frame to hold the armature lever in place.

The third object is accomplished by constructing the armature lever inan L-shape which increase armature inertia thereby reducing armaturebounce or chattering when the relay is energized, and affords an inertiamoment such that external shocks imposed on the relay have little effectin displacing the armature position.

The fourth object is accomplished by use of a U-shaped stationaryterminal having a threaded hole in each leg of the U with such holesbeing aligned and providing a terminal screw having threads adjacent itsouter end only with the remainder of the shank of the screw being smallenough to pass freely through the threaded holes. The housing is formedto receive the two legs of the contact so that a portion of the housingfits closely between such legs. When the threaded end of the screw hasbeen turned through the threads in the hole in the top leg the screwdrops down to the bottom leg and is screwed therein. The head of thescrew then captures a conductor against the top leg and compresses suchleg against the housing portion between the legs of the U.

Other objects and advantages will be pointed out in, or be apparent fromthe specification and claims, as will obvious modifications of the twoembodiments shown in the drawings in which:

FIG. 1 is a side sectional view of the relay of the present invention;

FIG. 2 is a front view of the relay;

FIG. 3 is an exploded view of the relay;

FIG. 4 is a partial sectional view taken on line 4--4 in FIG. 2 showingthe movable and stationary terminals in normally open position;

FIG. 5 is a partial sectional view similar to FIG. 4 showing the movableand stationary terminals in normally closed position;

FIG. 6 is a side view of the present relay adapted for DC. operation;and

FIG. 7 is a sectional view taken on line 7--7 in FIG. 6.

nited States Part 'ice Referring to the drawings, a molded housing 10provides a mounting base for the other parts of the relay.

In conventional relays having a separate core and mag net frame the coreis mounted directly on the magnet frame. Since the armature contacts thecore when the coil is energized this construction results in the wearallowance of the movable contacts being affected by the tolerances ofboth the core and the magnet frame. In the present construction thetolerances of thickness magnet frame 12 are eliminated fromconsideration in figuring the wear allowance for the contacts by theunique way in which the core 14 is mounted with respect to the magnetframe. A circular hole 16 is cut in the magnet frame large enough forthe core and a non magnetic eyelet 18 to pass therethrough. The frameseats on three very short upstanding spaced bosses 10a, 10b and whoseheights with respect to one another and to the portion of the housingwhich locates the stationary contacts can be closely controlled duringmolding of the housing. Dimples 17 pressed downward from the magnetframe are received in depressions 19 in the housing to properly locateand hold the frame on the housing. A boss 15 having the same height asthe bosses 10a, 19b and ltl-c control the mounted height of the core.The top end 26 of the core is enlarged either by mounting a D-shapedshading coil 21 therein (in AC. relays) or by providing a mushroomshaped head 23 (in DC. relays) which retains a spring washer 22 and acoil 24 thereon when such parts are mounted on the core from the bottomend. After the washer and coil are thus mounted on the core, the lowerend of the core is secured to the housing 16 by a screw which passesthrough the housing and into a threaded hole in the core. The screw istightened and this pulls the enlarged upper end of the core against thespring washer which holds the core and coil against housing. Since thecore passes through the magnet frame and seats directly on the housing,magnet frame thickness tolerances are eliminated from consideration infiguring the wear allowance for the movable contacts.

The construction and mounting of armature lever 26 of the presentinvention greatly reduces both armature bounce (and hence contactbounce) when the relay is energized and bouncing caused by vibrationsinduced by other devices mounted on a common panel. Lever 26 is L-shapedand is notched so that it slides over and pivotally cooperates with themagnet frame. The short leg of the armature serves to add mass toprovide it with an inertia moment inhibiting bounce when the longer legstrikes the core upon coil energization. The mass of the armature leveris distributed by the L-sha-pe construction so that shocks on the panelon which the relay is mounted tend to be canceled out as respects thelever thereby preventing externally induced lever bounce.

The top 28 of the L-shaped lever extends upwardly from its bearing onthe magnet frame past the end of coil core 14 and into engagement with amovable contact carrier 40 which is biased to normally hold lever 26 outof contact with the coil core. Lever 26 is held in place by a springplate or clip 30 which has a body portion 32 which extends throughnotches 34 in the magnet frame to hold lever 26 on the frame. Plate 30has an aperture 31 which snaps over projection 33 on lever 26 to holdthe plate in place. A tongue 36 projects upwardly from the plate bodyand into engagement with the contact carrier so that the plate is biasedto bear against the outside edges 38 of notches 34 in the magnet frame.The inherent flexure of the plate is such that it biases lever 26 intoengagement with the magnet frame. Thus the armature bears downwardlyagainst the frame when the coil is deenergized thereby insuring that thepick-up voltage at which the relay operates will be substantiallyconstant.

3 The spring plate also holds the armature in engagement with thecontact carrier.

The contact carrier 40 is slidably guided inside the housing by ribs 42and 44 on the carrier which mate with grooves 46 and 48, respectively,in the housing. These ribs are of a different size so that the carriercan only be assembled right side up in the housing. A notch '50 opensdownwardly from the carrier and the top portion of lever 26 extendstherein as well as the tongue of the spring plate. The sides of notch 50are arcuate to accommodate movement of the armature lever and springplate tongue when the carrier reciprocates. The carrier is biased towardthe housing exterior by a coil spring 52 which seats in a depression 54in the housing at one end and around a boss 56 on the carrier at theother end. The carrier has a window 58 therein in which a movablecontactor 59 is mounted by means of a spring 60 which fits around a pin62 projecting into the window at one end and bears against terminal 59at the other end. A pin 63 projects into the window from the other sideto provide a mount for the spring when the terminal is reversed. Theterminal has a central opening 64 through which such other pin projectswhen the terminal is in the position shown.

Another novel feature of this device is the way the stationary terminals66 are reversibly mounted to cooperate with the reversible movableterminals to provide either normally open or normally closed switchoperation. Each stationary terminal is U-shaped and has a silver contactplate 68 secured to the inside of one leg. The housing is apertured toaccommodate and orient the legs of each stationary contact so that oneleg is on either side of the movable contactor portions which extendlaterally from the contact carrier. Each stationary terminal is held inplace by a screw which passes through the legs of the terminal and thehousing. This screw has threads only adjacent its end and the remainderof its shank is of similar diameter than the root diameter of thethreads so that it is turned through the top leg and then drops down tothe other leg into which it is then screwed. Thus it does not engage thetop leg so that, when a wire is captured under the head of the screw,the screw head exerts a compressive force on the top terminal leg andforces it toward the bottom leg so that the legs tightly grip thehousing portion therebetween. This drop through feature also reduces thetime necessary to insert the terminal screw into operative position inthe stationary terminal. The contact carrier has a flange 70 on one endwhich catches on legs of the stationary terminals and serves to hold thecarrier in the housing when the movable contactor and stationaryterminals are in normally open position as shown in FIG. 4. When themovable contactor and stationary terminals are reversed as shown in FIG.5, a normally closed contact relay is provided. As shown in FIGS. 6 and7, when a DC. relay is desired, a pair of permanent magnets 72, whichaid in extinguishing the arcs, are inserted in grooves 74 in the housingand a mushroom headed core 73 is employed.

Assembly of the present device is quick and simple. The core, springwasher, coil and magnet frame are secured by a screw to the raised bossportions of the housing. Then the movable terminal is mounted in thecarrier and it is inserted in the housing. The stationary terminals arethen dropped into place and secured by the unique terminal screwsdescribed above. The notched armature lever is inserted on the end ofthe magnet frame and the top of the lever fits into the carrier notch.Then the spring plate is snapped in place and the relay is fullyassembled.

Although but two embodiments of the present invention have beenillustrated and described, it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the invention or from the scope of theappended claims.

I claim:

I. In an electromagnetic device, a housing, a movable contact carrierreciprocably mounted in said housing and having a notch formed thereinadjacent its outer end, a magnet frame mounted on said housing, anarmature lever pivotally mounted on an end of said frame and extendingat one end into the notch in said carrier, a spring plate anchoredintermediate its ends on said lever and at one end having a tongueprojecting into said notch to hold said lever against one side thereof,said magnet frame having notches adjacent the aforementioned end thereofso that the other end of said spring plate extends therethrough andbears against said frame to retain said lever on said frame.

2. The combination according to claim 1 wherein said armature lever isL-shaped, and the spring plate is anchored t0 the same lever arm that ispivotally mounted on said frame and has its end extending into the notchin said contact carrier.

3. The combination according to claim 1 wherein said spring plate isapertured intermediate its ends to snap over a complementally formedprojection on said lever to anchor said plate thereto.

References Cited in the file of this patent UNITED STATES PATENTS1,727,035 Prescott Sept. 3, 1929 2,246,183 Pepper June 17, 19412,589,167 Valkenburg et a1 Mar. 11, 1952 2,787,689 Stoecklin et a1. Apr.2, 1957 2,822,450 Goudy et a1. Feb. 4, 1958 2,892,053 Lambert et al June23, 1959 2,917,600 Smith Dec. 15, 1959 2,932,704 Dennison et al. Apr.12, 1960

1. IN AN ELECTROMAGNETIC DEVICE, A HOUSING, A MOVABLE CONTACT CARRIERRECIPROCABLY MOUNTED IN SAID HOUSING AND HAVING A NOTCH FORMED THEREINADJACENT ITS OUTER END, A MAGNET FRAME MOUNTED ON SAID HOUSING, ANARMATURE LEVER PIVOTALLY MOUNTED ON AN END OF SAID FRAME AND EXTENDINGAT ONE END INTO THE NOTCH IN SAID CARRIER, A SPRING PLATE ANCHOREDINTERMEDIATE ITS ENDS ON SAID LEVER AND AT ONE END HAVING A TONGUEPROJECTING INTO SAID NOTCH TO HOLD SAID LEVER AGAINST ONE SIDE THEREOF,SAID MAGNET FRAME HAVING NOTCHES ADJACENT THE AFOREMENTIONED END THEREOFSO THAT THE OTHER END OF SAID SPRING PLATE EXTENDS THERETHROUGH ANDBEARS AGAINST SAID FRAME TO RETAIN SAID LEVER ON SAID FRAME.